Railway Signaling and Communications Transformed by On-Site DX: Safe Equipment Management Supported by High-Precision Positioning

At the heart of safe railway operations are the signaling and communications installations placed along the track. Signals, level crossing devices, track circuits, communication cables, and other infrastructure control train movements and enable information exchange between drivers and traffic control. Ensuring these assets are installed and maintained at precisely the correct locations is essential for timetable adherence and accident prevention. Even slight installation errors or wiring mistakes can directly lead to accidents or operational disruptions, so installation and management of these systems demand very high accuracy. However, traditional challenges have long existed for on-site installation and maintenance work on signaling and communications equipment, such as ensuring positional accuracy and constraints of the working environment.

For example, even installing a single signal post requires meticulous surveying to place it exactly as shown on the plans. A small deviation in distance or angle from the track can affect signal sightlines or interfere with rolling stock. Nevertheless, much of this work is performed at night, requiring accurate installation within a limited time in the dark, which imposes a heavy burden on crews. Work areas alongside tracks are also extremely confined, and tasks must be done while paying attention to high-speed passing trains, so rigorous safety precautions are necessary.

Another challenge is the discrepancy between what is observed in the field and what is shown on design drawings. After years of site improvements and emergency works, it is not uncommon for the positions on drawings and the actual locations on site to differ. As a result, workers can spend significant time searching for equipment based on outdated drawings or comparing site photos to the actual location. Especially for buried cables, inaccurate historical records increase the risk of damaging other buried utilities during excavation. Additionally, the aging and shrinking workforce supporting field activities is becoming a serious issue, making it increasingly difficult to maintain traditional methods. Drawing attention as a key to resolving these on-site issues and achieving safe, efficient asset management are the use of high-precision positioning RTK and AR (augmented reality) navigation. By combining smartphone-based RTK positioning to achieve centimeter-level accuracy—so-called "LRTK" technology—installation and inspection tasks that once relied on craftsmen’s intuition and manual labor can be transformed. This article explains the challenges of conventional methods and details the benefits that high-precision positioning with LRTK and AR installation navigation bring to railway signaling and communications infrastructure management.

Field challenges encountered with conventional methods

• Labor-intensive surveying and accuracy limits: Traditionally, measuring positions for signal posts or identifying cable burial routes required tapes or total stations. These analog methods require setup and measurement time, and ensuring the precision demanded by railway works—often at the millimeter level—was constantly challenging. Small measurement errors can cause equipment misplacement, leading to rework or adjustments in subsequent processes.

• Difficulties working at night and in confined spaces: Performing work in the short nighttime window after train operations in limited spaces is a major constraint. Trackside areas have narrow footing and limited lighting, forcing surveying and construction under poor visibility. Simply transporting and setting heavy tripods and surveying instruments is burdensome, and sometimes there is no suitable location to set up equipment. In such environments, position-setting tasks take longer than usual and increase the physical load on workers.

• Inefficiency due to multiple personnel and manual procedures: Traditional surveying and equipment installation assumed teamwork. For example, surveying often required two-person teams—one holding a rod while the other operated the instrument—and verifying signal visibility sometimes required several workers on site to set up mock signals. Tasks that require many people and steps are inefficient in terms of staffing and coordination, and in sites suffering from manpower shortages, this becomes a heavy burden. The difficulty of securing personnel is an unavoidable problem for railway maintenance, where chronic labor shortages persist.

• Risk of human error and rework: Human errors such as misreading survey values or incorrect marking are also unavoidable. Careless mistakes when transcribing coordinates from paper drawings, misreading dimensions, or misunderstanding where to place marks can lead to equipment misplacement. If such misalignment is discovered after installation, major rework—like recasting concrete foundations or replacing equipment—may be necessary, seriously impacting schedules and costs.

• Discrepancies between drawings and field conditions: In asset management, outdated drawings or ledger information not matching actual field layouts have been problematic. Wiring routes may have changed over many renovations without updated drawings, or coordinates recorded under older geodetic datums may not align with current systems. Consequently, locating equipment based on drawings can be time-consuming, and there is a risk of excavating at incorrect locations. Reliance on drawings for inspection and construction invites inefficiencies from these information gaps.

• Safety risks during work: The working conditions described above also pose safety challenges. Night work tends to reduce attentiveness, and when workers enter near tracks, high places, or slopes to conduct surveys, the risk of accidents increases. Multiple people moving in a confined site raise the chance of contact injuries. Conventional methods, in pursuing efficiency and precision, place significant strain on site safety. In other words, the field has been caught in a dilemma where balancing efficiency and safety is difficult.

High-precision positioning and AR installation navigation enabled by LRTK

A trump card for solving the conventional challenges is the smartphone-based high-precision positioning system "LRTK". LRTK is a next-generation positioning system composed of a small RTK-GNSS receiver attached to a smartphone and a dedicated app. Using RTK (Real Time Kinematic) technology to correct satellite positioning errors in real time, it can measure the current position with centimeter-level accuracy. Where GPS once had meter-level errors, using LRTK means you can consistently determine positions that almost match design drawings. Attach an LRTK device to a smartphone and, when started in an open-sky location, high-precision positioning reception stabilizes in about 30 seconds, turning the phone into a pocket-sized surveying instrument.

A notable feature of LRTK is the AR installation navigation it provides. Because the target positions to be installed are visually overlaid on the smartphone camera view of the site, workers can be intuitively guided to the exact spot. For example, if planned coordinates for a signal post are loaded into the app in advance, simply pointing the phone on site will display guidance such as "move north by X cm, east by Y cm" in real time. By following the arrows and distance indicators on screen, a worker approaches the target, and the point where the displayed distance reaches zero is the installation point. The phone will show virtual stakes or markers on screen to indicate "this is the design-specified location," and the worker need only drive a real stake or mark that spot to complete accurate positioning. There is no longer a need to hold paper drawings and manually measure dimensions. Thanks to AR-based positional guidance, workers won’t lose sight of targets even at night or on complex terrain, allowing even inexperienced staff to place equipment at precisely the intended locations.

LRTK also includes functionality for 3D point cloud (scanning) measurement. Using a smartphone’s built-in LiDAR sensor and similar sensors, you can scan surrounding structures and terrain to record the site as point cloud data comprising tens of millions of points. Because RTK assigns absolute coordinates (latitude, longitude, height) to each point, the point cloud captured on site can be saved and used as a high-precision 3D model. For example, after installing a signal, scanning the surrounding area allows detailed desk-based verification of signal height, tilt, and positional relationships. If you scan burial trenches before backfilling, you can preserve the location of underground cables as digital data for future reference. This point cloud data can be shared and viewed on the cloud, and on-site users can easily take sections to measure dimensions or automatically calculate backfill volumes. Of course, the acquired point cloud data can be used to update construction drawings and CIM models and directly contributes to electronic delivery of as-built documentation.

Position data, point clouds, and photos collected by LRTK are uploaded to the cloud in real time. This not only enables instant data sharing between site and office but also plots acquired coordinates on maps so the whole team can reference them later. Photos taken with a smartphone are tagged with high-precision location information, eliminating uncertainty about where a photo was taken. Such digital linkage allows assets that previously required cross-checking with drawings to be intuitively managed on GIS maps or 3D models.

LRTK devices are also very compact and cost-effective, making it easy to equip each worker to perform positioning and recording whenever needed. With LRTK’s adoption, field work styles change dramatically. With one smartphone per person, the personnel once required for surveying can be reduced, and each worker can immediately perform positional measurements and installations for their assigned area. High-precision guidance prevents measurement mistakes and enables correct installation on the first attempt, greatly reducing rework. This shortens night work intervals and reduces the number of personnel on site, dramatically improving safety. Because tasks can be performed accurately based on data rather than relying on veteran intuition, quality variation is reduced. LRTK provides a DX solution for railway infrastructure installation and maintenance that delivers efficiency, quality, and safety. In one construction case where LRTK was used for stake setting, reported time to set survey points was reduced to about one-sixth compared with conventional optical surveying. The number of points that can be processed in a day dramatically increased, directly contributing to schedule shortening and cost reduction.

Specific field scenarios using LRTK

• Use for signal post installation: Traditionally, new signal post construction required repeatedly measuring distance from the track center to determine foundation positions and verifying sightlines from a driver's perspective after installation. With LRTK, the phone guides the installation location on site based on design coordinates, enabling placement of the post base in the correct position in a single step. For example, even during late-night work, simply driving the stake indicated by the AR marker on the phone screen completes the position-setting. If you record the post location with a point cloud scan after erection, you can accurately check later whether the post is vertical and at the specified height. This streamlines sightline and clearance confirmation and reduces the need for large crews to perform repetitive checks on site. Because large-scale manual verification becomes unnecessary, the number of personnel working on the tracks at night is minimized, contributing to improved safety.

• Use for communication cable burial: When burying communication cables along railway lines, workers traditionally marked the ground based on plan routes and recorded burial locations after excavation via photos and manual measurements. Insufficient records can leave the risk of interference with other utilities during future excavations. Introducing LRTK makes it possible first to visualize the excavation route in AR before construction. Pointing a phone at the ground displays the planned route as a line, so workers intuitively know "this is where to dig." After burial, the trench and cable can be scanned with the phone and accurately recorded as point cloud data in the cloud before backfilling. Later, by viewing the ground through the phone, workers can AR-see-through to the underground cable locations and avoid accidental damage during other works. Preserving burial locations as accurate digital records also facilitates sharing information with future contractors, smoothing handovers and pre-work coordination. The ability to retain and use buried-asset information as digital data greatly improves future maintenance quality.

• Use for inspection records of communications equipment: Regular inspection and adjustment of signaling and communications equipment is essential. Traditionally, inspectors carried drawings with numbered assets and filled out checklists or took photos on site. Using LRTK, inspection work becomes digital. As personnel patrol with a smartphone, their precise location is known, and a map or AR view instantly shows which assets nearby require inspection. Inspection results are entered on the phone and photos are saved to the cloud with location tags. For example, when inspecting the inside of a level crossing control cabinet or a signal control box, photos become automatically linked to the location (e.g., "internal wiring of the north control box at XX level crossing"), making report creation straightforward. Historical inspection records are viewable on maps, helping prevent oversights and missed inspections. If you want to check for abnormal installation conditions, you can use scanned point cloud data to measure tilt or positional changes. By accumulating data through LRTK, maintenance work becomes visualized and recorded in real time, allowing field staff and the management department to share the same information for assessing asset health. Completing data entry and sharing on site significantly reduces post-processing work such as report drafting and improves the overall efficiency of the maintenance cycle. Analyzing accumulated data also opens the door to predictive maintenance, such as detecting failure precursors.

Closing remarks

Digital-driven on-site DX (digital transformation) is finally taking hold in the railway industry. The use of LRTK in signaling and communications asset management is emblematic of this trend. Solutions that combine high-precision positioning, AR navigation, and 3D scanning transform manual tasks into data-driven operations, dramatically improving safety, workmanship, and efficiency. Being able to complete construction and inspections accurately within the limited night work windows without errors is of immeasurable value to the teams that support safe train operations.

Another major advantage of LRTK is its low barrier to on-site adoption. It does not require special machinery or large-scale systems; simply attaching a small device to an existing smartphone allows staff to start using it with minimal disruption to daily routines. With all data centrally managed in the cloud, the need to repeatedly update paper drawings and ledgers is eliminated, turning tacit knowledge into shared organizational assets. When veterans and younger staff alike collaborate using the same digital tools, the generation-gap in field expertise can be bridged. Real-time data from the site can be seamlessly shared with management and other departments, enabling quick, organization-wide decision-making based on a clear understanding of field conditions.

The safety, certainty, and speed required for railway signaling and communications equipment management are exactly the outcomes that LRTK-enabled on-site DX delivers. Smartphone RTK-based construction management is already spreading in domestic construction and civil engineering, and the railway maintenance sector is following suit. The Ministry of Land, Infrastructure, Transport and Tourism is strongly promoting DX in infrastructure through initiatives like i-Construction, and with the full enforcement of the 2024 construction industry work-style reform-related law, reducing night work hours has become an urgent issue. In these circumstances, adopting digital technologies like LRTK is a powerful solution for simultaneously improving productivity and ensuring safety on site. To support increasingly complex and sophisticated infrastructure in the future, innovating field work itself is indispensable. The "big transformation beginning with a small device" will help make the future of railway field operations secure. I sincerely hope you will consider introducing the high-precision technology LRTK into the world of railway signaling and communications transformed by on-site DX to achieve both safety and productivity. Now is an era in which field capabilities that protect railway safety can be further strengthened by digital power. Let us harness digital technology together to pass safe, resilient railway infrastructure on to the next generation.